A high-pressure tank is used as a supply source of a fuel gas in, for example, a fuel cell system disposed in a vehicle such as a car. Generally, the high-pressure tank comprises: a metal mouthpiece attached to both ends of a tank main body in its axis direction; and a reinforcing fiber layer formed by winding a reinforcing fiber around over the outer circumferential surface of the tank main body and the outer circumferential surface of the mouthpiece by a filament winding process.